This invention relates to the control of temperatures during a setback period normally occurring at night. In particular, this invention relates to the automatic control of the setpoint temperature for a heating, venting and air conditioning (HVAC) system during such a period.
Thermostatic control of nighttime temperatures during normal sleeping hours is well known in the art. This is quite often accomplished by a programmable thermostat which allows a person to define one or more setback temperatures that are to be maintained for predetermined periods of time. The thermostatic control is thereafter operative to implement the setback during the predetermined periods before returning to the previous temperature or to a new temperature in the morning.
The above thermostatic control requires that programmable entries be made by a person. Each programmable entry by the person may require several steps to select and store a temperature that is to occur at a given time. The particular selection of temperatures may not have been done with regard to the need to avoid a sharp drop or rise in temperature which may produce an uncomfortable sleeping environment. The above personally programmed control may also not take into account changes in the season wherein the temperature may need to be relaxed differently when heating versus cooling is being required of the HVAC unit.